Machines for automatically manufacturing packaging are known. Further, machines for manufacturing packaging having more than one component, such as a blank with an opening cut therein over which a clear plastic window is placed, are also known.
In the operation of these manufacturing machines, timing is critical. Specifically, cardboard blanks are delivered to a conveyor by a feeder. The aperture over which a window is attached faces upwards. The conveyor then transports the blank underneath a rotary placer, which is also known in the art. The rotary placer then places a clear plastic window over the aperture of the blank, which is still disposed on the moving conveyor. The operation is carried out continuously. Accordingly, the timing of the delivering of the blank to the conveyor and the movement of the conveyor under the designated point underneath the rotary placer where the clear window is applied to the aperture is crucial. Inaccurate timing in any of the above-referenced steps will result in the window not being accurately placed over the aperture of the blank, i.e. either too high or too low.
At the beginning of the operation, the blank must be delivered to the moving conveyor in a precise and accurate manner. The apparatus designated to deliver the blanks to the conveyor, one at a time, is commonly referred to as a feeder. Currently available feeders include a magazine which accommodates a stack of blanks. The blanks are disposed in a generally horizontal fashion. The lowermost blank of the stack engages a moving conveyor and is drawn off the bottom of the stack.
The above-described design has a number of disadvantages. First, as the stack of blanks gets smaller, the amount of weight imposed on the lowermost blank by the stack changes. Thus, the frictional engagement between the lowermost blank and the belt which draws the lowermost blank from the bottom of the stack varies. This variation in the magnitude of frictional engagement between the lowermost blank and the moving belt causes problems in terms of the accuracy in which the lowermost blank is drawn off the bottom of the stack. For example, when the stack is small, and little weight is applied to the top of the lowermost blank, slippage can occur between the lowermost blank and the moving belt. As a result, the position of the blank on the belt may be shifted which will be translated later down the line. Consequently, the window may not be accurately placed over the aperture in the blank.
Further, if the stack is too high, and the weight imposed on the lowermost blank is too great, slippage again may occur which would change the position of the blank on the belt from the desired position. As a result, the position of the aperture of the blank underneath the rotating placer once the blank arrives at the rotating placer will not be accurate and the window will not be accurately applied to the blank.
Further, another disadvantage involves the belt drawing more than one blank off the bottom of the stack. Specifically, a belt can often grab the lowermost blank and the blank disposed immediately on the top of it which results in two blanks being disposed on the same area of the belt at the same time. This of course can lead to jamming in other mechanisms down the line, the inaccurate placement of the blanks on the belt and the inadvertent production of blanks without a window.
Accordingly, there is need for an improved feeder mechanism for feeding blanks, such as cardboard blanks, and other items of manufacture, one at a time and in an accurate manner to a moving conveyor belt.